LONDON -- The issue of an independent nuclear deterrent has now once again become a prime topic of debate in Britain.

Of course, the question of whether Britain should retain nuclear weapons has been a subject of fierce political argument all along since the atomic bombings of Hiroshima and Nagasaki in World War II. But somehow the outcome has always been a foregone conclusion.

Britain had to keep its nuclear weapons as long as other states were threatening the world with such horrific weapons. National security, went the argument, depended on deterrence, on sending the clear message that any nuclear attack would mean nuclear retaliation and that the attacker would be inviting annihilation -- the so-called theory of mutually assured destruction.